Note that this is not all writing of optical media, much less reading of optical media, but specifically packet writing, a comparatively rarely-used set of functionality to provide the appearance of limited modifiability on write-once media.

https://en.wikipedia.org/wiki/Packet_writing

Packet writing allows users to create, modify, and delete files and directories on demand without the need to burn a whole disc. Packet writing technology achieves this by writing data in incremental blocks rather than in a single block.

Deleting files and directories of a CD-R using packet writing technology does not recover the space occupied by these objects but, rather, they are simply marked as being deleted (making them effectively hidden). Similarly, changes to files cause new instances to be created instead of replacing the original files. Because of this, the available space on a non-rewritable medium using packet writing technology will decrease every time its content is modified.

I've burned many optical media discs, but never made use of packet writing.

EDIT: I think that wodim is probably the most-commonly-used optical media burning software for data discs on Linux, and looking at its man page, it apparently never got packet writing support out of being flagged experimental, for perspective:

   -packet
          Set Packet writing mode.  This is an experimental interface.

   pktsize=#
          Set the packet size to #, forces fixed packet mode.  This is an experimental interface.

   -noclose
          Do not close the current track, useful only when in packet writing mode.  This is an experimental interface.